Window heating systems of the generic type are known. They usually possess a resistance heating device that is constituted in the form of electrical conductors arranged in meandering fashion on the window that is to be heated. The electrical conductors are applied onto a surface of the window as thin, planar or linear conductive strips or, in the case of composite windows, are integrated into a window pane cavity. When the resistance heating device is connected to a heating voltage source, usually the motor vehicle battery, the flow of an electrical current results in heating of the resistance heating device, which thereupon warms up the window that is to be heated.
In order to connect the resistance heating device to the heating voltage source, it is known to use an electrical switching means that can be activated by an operator of the motor vehicle. The electrical switching means are, for example, relays. These are usually arranged on a circuit board arranged in the instrument panel of the motor vehicle. It is further known to use, instead of the mechanical relays, semiconductor switching means, for example power transistors, although for adaptation to existing contact structures of the mechanical relays they are placed in adapter housings. Besides the additional costs associated therewith as a result of the use of the adapter housing, installation on a circuit board arranged below an instrument panel of the motor vehicle is relatively complex.